Professional Android 4 Application Development Notes

Professional Android 4 Application Development

Chapter 1

Introducting the development framework

Android applications normally are written using Java, and executed by Dalvik VM.

Each Android application runs in a separate process within its own Dalvik instance.

SDK

NDK

Android Application Architecture

Activity Manager and Fragment Manager

to control the lifecycle of your Activities and Fragments

Views

to construct the UI

Notification Manager

to provide a consistent and nonintrusive mechanism for signaling your uses

Content Providers

let your applications share data

Resource Manager

enables non-code resources,such as strings and graphics

Intents

provide a mechanism for transferring data between applications and their components

Chapter 2

Android Development Tools

Android Virtual Device and SDK Managers

to create and manage AVDs

to download SDK packages

Android Emulator

DDMS (Dalvik Debug Monitoring Service)

to interrogate active processes

to view the stack and heap

to watch and pause active threads

to explore the filesystem

ADB (Android Debug Bridge)

a client-server application

a daemon running on the device

a server runs on PC

logcat

to view and filter the output of the Android logging system

AAPT (Android Asset Packaging Tool)

additional tools

ADT plug-in

SQLite3

Traceview and dmtracedump

Hprof-conv

Dx

to convert Java .class bytecode into Android .dex bytecode

Hierarchy Viewer

to debug and optimize UI

to analyze, debug, and optimize the XML layout defi nitions

Lint

to optimize your layouts

to analyze and optimize your application and resources

Draw9patch

to simplify the creation of NinePatch graphics

Monkey and Monkey Runner

Monkey runs within the VM, generating pseudo-random user and system events.

Monkey Runner provides an API for writing programs to control the VM from outside your application.

to test your applications stability from a UI perspective

ProGuard

to shrink and obfuscate your code

to make your code more difficult to reverse engineer

Chapter 3

What makes an Android Application ?

Activities

The UI of your application is built around one or more extensions of the Activity class.

Activities use Fragments and Views to layout and display information, and to respond to user actions.

Services

Service components run without a UI,updating your data sources and Activities, triggering Notifi cations, and broadcasting Intents.

to perform long running tasks, or those that require no user interaction

Content Providers

to manage application data and interact with SQL databases

to share data across application boundaries

Intents

interapplication message-passing framework

explicit, implicit and broadcast Intents

Broadcast Receivers

Intent listener

to listen for Intents that match the criteria you specify

Widgets

visual application components that are added to the home screen

Notifications

to alert users to application events without stealing focus or interrupting their current Activity

Introducing the Application Manifest file

A Closer Look at the AndroidManifest.xml

<manifest xmlns:android=”http://schemas.android.com/apk/res/android”
package=“com.paad.myapp“
android:versionCode=“1“
android:versionName=“0.9 Beta“
android:installLocation=“preferExternal“>
[ ... manifest nodes ... ]
</manifest>

The manifest tag can include nodes that define the application components, security settings, test classes, and requirements that make up your application.

available manifest sub-nodes

uses-sdk

to define a minimum and maximum SDK version

to define the target SDK version

<uses-sdk android:minSdkVersion=”6”
android:targetSdkVersion=”15”/>

uses-configuration

to specify input mechanisms that are support by your application

be useful for games that require particular input controls

any combination of reqFiveWayNav, reqHardKeyboard, reqKeyboardType, reqNavigation, reqTouchScreen

for example, a device with a finger touchscreen, a trackball, and either a QUERTY or a twelve-key hardware keyboard, as shown here:

<uses-configuration android:reqTouchScreen=”finger”
android:reqNavigation=”trackball”
android:reqHardKeyboard=”true”
android:reqKeyboardType=”qwerty”/>

<uses-configuration android:reqTouchScreen=”finger”
android:reqNavigation=”trackball”
android:reqHardKeyboard=”true”
android:reqKeyboardType=”twelvekey”/>

uses-feature

to specify which hardware features your application requires

this prevents your application from being installed on a device that doesn’t include a required piece of hardware, such as NFC, as follows:

<uses-feature android:name=”android.hardware.nfc” />

optional hardware features: audio, bluetooth, camera, location, microphone, nfc, sensors, telephony, touchscreen, usb, wifi

supports-screens

to specify the screen size

On devices with supported screens, your application is laid out normally using the scaling properties associated with the layout files you supply.

On unsupported devices the system may apply a “compatibility mode,” such as pixel scaling to display your application.

<supports-screens android:smallScreens=”false”
android:normalScreens=”true”
android:largeScreens=”true”
android:xlargeScreens=”true”
android:requiresSmallestWidthDp=”480”
android:compatibleWidthLimitDp=”600”
android:largestWidthLimitDp=”720”/>

supports-gl-texture

uses-permission

to declare the user permissions your application requires

<uses-permission    android:name=”android.permission.ACCESS_FINE_LOCATION”/>

permission

to create permissions to restrict access to shared application components

instrumentation

to provide a test framework for your application components at run time

to monitor your application and its interaction with the system resources

application

to specify the metadata for your application

A manifest can contain only one application node

The application node also acts as a container for the Activity, Service, Content Provider, and Broadcast Receiver nodes that specify the application components

<application android:icon=”@drawable/icon”
android:logo=”@drawable/logo”
android:theme=”@android:style/Theme.Light”
android:name=”.MyApplicationClass”
android:debuggable=”true”>
[ ... application nodes ... ]
</application>

application sub-nodes

activity

An activity tag is required for every Activity within your application. Trying to start an Activity that’s not defi ned in the manifest will throw a runtime exception.

Each Activity node supports intent-filter child tags that define the Intents that can be used to start the Activity

<activity android:name=”.MyActivity” android:label=”@string/app_name”>
<intent-filter>
<action android:name=”android.intent.action.MAIN” />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

service

a service tag for each Service class used in your application.

Service tags also support intent-filter child tags to allow late runtime binding.

<service android:name=”.MyService”>
</service>

provider

Provider tags specify each of your application’s Content Providers.

Content Providers are used to manage database access and sharing.

<provider android:name=”.MyContentProvider”
android:authorities=”com.paad.myapp.MyContentProvider”/>

receiver

Each receiver node supports intent-filter child tags that define the Intents that can be used to trigger the receiver

<receiver android:name=”.MyIntentReceiver”>
<intent-filter>
<action android:name=”com.paad.mybroadcastaction” />
</intent-filter>
</receiver>

uses-library

to specify a shared library that this application requires

You can specify that a particular package is required — which prevents the application from being installed on devices without the specifi ed library — or optional, in which case your application must use refl ection to check for the library before attempting to make use of it

<uses-library android:name=”com.google.android.maps”
android:required=”false”/>